12 kV, 36 kV and 145 kV distribution circuit breakers-an independent review

Distribution and transmission voltage ranges can vary widely from country to country. In the UK, the distribution network is up to 145 kV while transmission voltages are 300 kV and 420 kV. The regional electricity distribution companies (RECs) are responsible for system voltages up to 145 kV for their primary distribution network. In this context the primary voltage refers to the first stage of bringing the high voltage supplies to the substations which is then conveyed to the centres where it is converted to medium or low voltages for domestic or industrial uses. This paper deals with circuit breakers for the primary voltages up to 145 kV, describes their design, development and service experience. It examines different arc interruption techniques and addresses some practical issues. The author also identifies some areas of concern and illustrates them by case studies